1. Field of the Invention
The present invention relates to a two dimensional data input device for a computer system, and more particularly to a cursor positioning device for controlling the movement and positioning of a cursor on a computer display.
The present invention is a further improved cursor-positioning device of my PCT Application Numbers PCTCN950042 and PCTCN950043.
2. Description of the Prior Art
The conventional cursor control devices or cursor positioning devices for a computer monitor include keyboard, mouse, trackball, touch screen, light pen, and so on. These prior art cursor positioning devices are widely used to control the cursor movement and positioning of the cursor or mark on the computer display. Nowadays, these prior art cursor-positioning devices are also widely applied to a computer system as a function selection device to simply perform specific function on menus for a computer application program.
However, it is found that these conventional cursor-positioning devices are not very convenient in performing the cursor moving operation. For example, the well-known computer keyboard suffers from significant slow performing speed during controlling the cursor movement. It is also noted that the computer mouse is not convenient in cursor movement because the user must move the mouse within a large square area on a mouse pad or a smooth desk by moving his arm repeatedly. In addition, the conventional computer mouse typically includes a downward rotable ball and two encoder wheels to detect the movement of the mouse, which always suffers from contamination, causing poor performance reliability.
In order to overcome the drawbacks found in the conventional cursor positioning devices, "Absolute Axis Coordinate" type computer pointing devices are disclosed in U.S. Pat. Nos. 4,782,327 and 4,935,728. However, both the prior art U.S. patents have a relatively larger structure size with a complicated control circuit interface and a complicated control procedure to achieve the cursor moving control purpose.
One important problem of the prior art is described below. The typical horizontal resolution of the computer screen may be 640, 800 or 1280 pixels. During slow movement operation mode of the prior art, the cursor on the screen is operated in a pixel-to-pixel operation mode, i.e. fine displacement mode. In case that the finger controllable member of the pointing device moves 320 pixels, the cursor on the screen only moves half of the total traveling distance of the screen or less. At this time, in case that the user changes the operation mode of the pointing device from the initial slow operation mode to a fast movement operation mode, the cursor on the screen will directly jump to the forward margin on the screen or move over 640 pixels. It is to be understood that the prior art has disadvantage of suddenly jumping feature, causing sudden change operation feeling during moving operation. Because the distance of the cursor moving on the display is equal to a product of a distance of the cursor from an edge of the display area of movement times a quotient of a detected distance of movement of the finger-grippable element divided by a distance of the finger-grippable element from an edge of the pointer area of movement, so it is possible to get a fraction during operation.
The former method will tire the user due to the length of the finger controllable member is increased, especially the operating range is limited in left and right direction in movement. The second method above will has problem that it can not correctly generate a signal at each moving time because that the distance is decreased causing a small effective displacement. Moreover, it is possible to cause a problem that the pointing device generates two or three pulse signals at each moving time. The design of shorten the distance of photo encoder can reduce the operating ranges of user hand during moving the finger controllable member, and it is especially applicable in use of remote controller for a multi-media system with more convenience and comfort.
The moving speed of the movable photo encoder of the present invention is designed to be proportional to the displacement of the movable photo encoder. So, it is highly possible to control the cursor within a small operating region of 16 mm, by reducing the length of the movable photo encoder, i.e. reducing the operation distance of the finger controllable member, under control of firmware.